Comments on binarymillenium: Structured Light For 3d Scanning

Thanks for the quick reply, I reposted on the goog...

2010-01-31T14:10:20.404-08:00

Thanks for the quick reply, I reposted on the google groups forum you linked.

fisj, One method to reduce the tearing that works...

2010-01-31T13:09:02.529-08:00

fisj,

One method to reduce the tearing that works decently (though is costly in capture time) is to do at least three passes at different frequencies, and take the median of the unwrapped phases.

One thing I haven't tried (for a single pass) would be to 'seed' the phase unwrapping at different locations and not just the center, though that are still on the target (and not on masked off areas), and take the median of those.

Another thing to try is to have three variations on the standard flood fill, ones that for example fill more preferentially in different directions, and median the results.

You might want to move discussion over to http://groups.google.com/group/structured-light. Also share a link to your source. Also if you want you could probably host it within the Structured Light google code project.

I've been porting Kyle's code to c#, and it looks ...

2010-01-31T12:48:04.018-08:00

I've been porting Kyle's code to c#, and it looks like I've run into some similar tearing issues when unwrapping the phases.

Any idea whats causing this? At first I just assumed it was poor masking, and the inability of the flood fill to handle it. However, I get different tears on the same pixels with different thresholding.

I've created a pretty close port, so its difficult for me to see exactly what the difference is.

Aha, I just read through it some more and I realiz...

2010-01-05T14:31:44.576-08:00

Aha, I just read through it some more and I realize now that you're using the same algorithm. I thought maybe you were using someone else's unwrapping algorithm.

This is awesome to see the Matlab result... I'm su...

2010-01-05T14:28:33.915-08:00

This is awesome to see the Matlab result... I'm surprised it's so glitchy, I feel like I have some algorithms on paper that would be more accurate.

Regarding higher resolution as a target, the direction I'd like to take for this is a combination of phase shift and gray code. Imagine a gray code pattern, but using a sine wave instead of a square wave. The gray code part solves the depth discontinuity issue. The phase shift part solves resolution.

Geometric Informatics has a demo video where it looks like they're doing something similar to this: http://www.youtube.com/watch?v=EPTt2HgGYYQ at 2:47

I already have a generator for these patterns if you're interested in working with me on the decoding.